e28d0c73d4d7adc9cd3747d81fdc7338217f9a0c - hwmon: add driver for ARCTIC Fan Controller

Fri, 08 May 2026 08:44:00 +0200

hwmon: add driver for ARCTIC Fan ControllerAdd hwmon driver for the ARCTIC Fan Controller, a USB HID device(VID 0x3904, PID 0xF001) with 10 fan channels. Exposes fan speed inRPM (read-only) and PWM duty cycle (0-255, read/write) via sysfs.The device pushes IN reports at ~1 Hz containing RPM readings. PWM isset via OUT reports; the device applies the new duty cycle and sendsback a 2-byte ACK (Report ID 0x02). The driver waits up to 1 s forthe ACK using a completion. Measured device latency: max ~563 ms over500 iterations. PWM control is manual-only: the device never changesduty cycle autonomously.raw_event() may run in hardirq context, so fan_rpm[] is protected bya spinlock with irq-save. pwm_duty[] is also protected by this spinlockbecause reset_resume() clears it outside the hwmon core lock. The OUTreport buffer is built and write_pending is armed under the same lock sothat no reset_resume() can race with the pwm_duty[] snapshot. priv->bufis exclusively accessed by write(), which the hwmon core serializes.Signed-off-by: Aureo Serrano de Souza Link: https://lore.kernel.org/r/20260508064405.38676-1-aureo.serrano@arctic.deSigned-off-by: Guenter Roeck List of files: /linux/drivers/hwmon/arctic_fan_controller.c

Changes in arctic_fan_controller.c

e28d0c73d4d7adc9cd3747d81fdc7338217f9a0c - hwmon: add driver for ARCTIC Fan Controller